ELECTRICAL IMPEDANCE IMAGING METHOD, SYSTEM AND STORAGE MEDIUM

Description

Field of the Invention

[0001] The present disclosure pertains to the field of electrical impedance imaging technology, and in particular relates to a method, a system and a storage medium for electrical impedance imaging.

Background of the Invention

[0002] Current electrical impedance imaging techniques can only produce instantaneous electrical impedance change images, such as ones caused by instantaneous ventilation or blood perfusion. However, the instantaneous electrical impedance change images, such as blood perfusion images, change rapidly when displayed, which is detrimental to the understanding of the image by an observer. Moreover, the instantaneous electrical impedance change images often show relatively large differences in different human physiological cycles (e.g.,the cardiac cycle), making it difficult for the observer to understand the overall functional state (e.g., ventilation or blood perfusion) of a tested human body area over a period of time.

Prior Art

[0003] US 2003/21664 A1 refers to a method and an apparatus for displaying information obtained by electrical impedance tomography (EIT) data from a part of a patient's body.

[0004] WO 2020/199367 A1 shows an electrical impedance tomography apparatus and method. The electrical impedance tomography apparatus is applicable to medical imaging, can employ an in vivo electrode to perform multi-frequency-one-time excitation and measurement on a biological tissue under test and use a measured complex voltage signal to perform three-dimensional image reconstruction, and can simultaneously display ventilation and perfusion images in real time.

Summary of the Invention

[0005] The present disclosure presents a method, a system and a storage medium for electrical impedance imaging, precisely based on the technical problem that it is difficult to reflect the overall state of a tested human body through instantaneous electrical impedance change images.

[0006] In a first aspect, the present disclosure provides an electrical impedance imaging method according to claim 1. The method comprises: acquiring electrical impedance measurement signals of a tested human body area at a plurality of measurement times; for the electrical impedance measurement signal at each measurement time, constructing a corresponding instantaneous differential image on the basis of the electrical impedance measurement signal; constructing an image matrix on the basis of the instantaneous differential images at the plurality of measurement times, wherein each column in the image matrix is a vector corresponding to respective instantaneous differential image; determining, on the basis of the image matrix, a covariance matrix corresponding to the image matrix; obtaining, according to the covariance matrix, a weight vector of the covariance matrix; and obtaining, on the basis of the covariance matrix and the weight vector, an electrical impedance state image of the tested human body area.

[0007] The image matrix is:

where I is the image matrix, a(t₁) is a vector corresponding to the instantaneous differential image at a first measurement time, a(t₂) is a vector corresponding to the instantaneous differential image at a second measurement time, and a(t_N) is a vector corresponding to the instantaneous differential image at an N-th measurement time.

[0008] The invention further comprises: calculating, on the basis of the image matrix, the covariance matrix corresponding to the image matrix by using a first predetermined computational equation, wherein, the first predetermined computational equation is:

where C is the covariance matrix, I is the image matrix, T is a transpose of the matrix, I is a time-averaged matrix with the size of M * N, and each column element in the time-averaged matrix is

, where M is the number of pixels in each frame of instantaneous differential images, N is the number of measurement times, and a(t_i) is a vector corresponding to the instantaneous differential image at the i-th measurement time.

[0009] It further comprises: calculating the weight vector of the covariance matrix according to the covariance matrix by using a second predetermined computational equation, wherein the second predetermined computational equation is:



where w_* is the weight vector, w is a column vector with the size of M * 1, the value of elements in the column vector is 1 or -1, T is a transpose of the matrix, and C is the covariance matrix.

[0010] Optionally, the obtaining, on the basis of the covariance matrix and the weight vector, an electrical impedance state image of the tested human body area, further comprises: calculating, on the basis of the covariance matrix and the weight vector, the electrical impedance state image of the tested human body area by using a third predetermined computational equation, wherein the third predetermined computational equation is:

where a_s is the electrical impedance state image, C is the covariance matrix, and w_* is the weight vector.

[0011] Optionally, the for the electrical impedance measurement signal at each measurement time, constructing a corresponding instantaneous differential image on the basis of electrical impedance measurement signal, further comprises: for the electrical impedance measurement signal at each measurement time, extracting a signal in a predetermined frequency range from the electrical impedance measurement signal; and for each extracted signal in the predetermined frequency range, constructing a corresponding instantaneous differential image on the basis of the extracted signal in the predetermined frequency range by using an image reconstruction algorithm.

[0012] Optionally, the image reconstruction algorithm comprises a linear least square method.

[0013] In a second aspect, the present disclosure provides an electrical impedance imaging system according to claim 8.

[0014] In a third aspect, the present disclosure provides a storage medium according to claim 9.

[0015] In the method, the system and the storage medium for electrical impedance imaging provided in the present disclosure, an electrical impedance state image, which reflects the overall state of a tested human body function over a period of time, is reconstructed from the electrical impedance measurement signals of the tested human body area at a plurality of measurement times. As can be seen, the electrical impedance imaging method provided in the present disclosure can be used to obtain an electrical impedance state image that reflects the overall state of the tested human body function over a period of time, thereby facilitating the understanding of images and the overall grasp of the tested human body function by an observer for subsequent qualitative and quantitative analysis of the tested human body function.

Brief Description of the Drawings

[0016] The scope of the present disclosure may be better understood by reading the detailed description of exemplary examples below in conjunction with the drawings. The drawings included herein are:

FIG. 1 illustrates a schematic flow diagram of an electrical impedance imaging method provided in Example 1 of the present disclosure;

FIG. 2 illustrates an effect picture of an electrical impedance state image of three-dimensional blood perfusion in a human thoracic cavity.

Detailed Description of the Invention

[0017] In order to make the purpose, technical solutions and advantages of the present disclosure clearer, the implementation method of the present disclosure will be described in detail below in conjunction with the drawings and examples, whereby the implementation process of how technical means can be applied in the present disclosure to solve technical problems and achieve technical effects, can be fully understood and carried out accordingly.

[0018] While many specific details are set forth in the following description to facilitate a full understanding of the present disclosure, the present disclosure may also be implemented in other ways different from those described herein, and therefore the protection scope of the present disclosure is not limited by the specific examples disclosed below.

Example 1

[0019] According to examples of the present disclosure, an electrical impedance imaging method is provided, and FIG. 1 illustrates a schematic flow diagram of an electrical impedance imaging method provided in Example 1. As shown in FIG. 1, the electrical impedance imaging method may include steps S110 to S160 as follows.

[0020] In step S110, electrical impedance measurement signals of a tested human body area is acquired at a plurality of measurement times.

[0021] Here, the electrical impedance measurement requires first fixing an electrode array containing a number of electrodes around the tested human body area, and then exciting the tested human body area by the electrode array and measuring the resulting response. For example, the electrical impedance measurement signals are obtained by applying current excitation to the electrodes in turn and successively measuring the resulting voltage signals at other electrodes.

[0022] The plurality of measurement times means that the electrical impedance measurement is performed on the tested human body area several times over a continuous period of time, thereby obtaining the electrical impedance measurement signals at the plurality of measurement times.

[0023] In step S120, for the electrical impedance measurement signal at each measurement time, a corresponding instantaneous differential image is conducted on the basis of the electrical impedance measurement signal.

[0024] Here, after the electrical impedance measurement signal is obtained, the corresponding instantaneous differential image can be constructed on the basis of the electrical impedance measurement signal. If there are five measurement times, the instantaneous differential image corresponding to each of the five measurement times can be obtained.

[0025] The instantaneous differential image reflects the change in electrical impedance of the tested human body area at the measurement time of the reconstruction of the instantaneous differential image with respect to a reference time (e.g., the time corresponding to the end of expiration).

[0026] In an optional embodiment, in step S120, for the electrical impedance measurement signal at each measurement time, constructing a corresponding instantaneous differential image on the basis of the electrical impedance measurement signal, comprises steps S121 to S122 as follows.

[0027] Step S121, for each electrical impedance measurement signal at each measurement time, a signal in a predetermined frequency range is extracted from the electrical impedance measurement signal.

[0028] Step S122, for each extracted signal in the predetermined frequency range, a corresponding instantaneous differential image is constructed on the basis of the extracted signal in the predetermined frequency range by using an image reconstruction algorithm.

[0029] Here, in step S121, a signal in the predetermined frequency range is extracted from the electrical impedance measurement signals on the basis of the time-frequency characteristics of signals. The predetermined frequency range may be in a ventilation frequency range, then the extracted signal is a ventilation-related signal; and the predetermined frequency range may be in a blood perfusion frequency range, then the extracted signal is a blood perfusion-related signal. Specifically, a signal in the predetermined frequency range can be extracted from the electrical impedance measurement signals by using a filter.

[0030] After being extracted, the signal in the predetermined frequency range is used to construct a instantaneous differential image by an image reconstruction algorithm. The image reconstruction algorithm may be a differential reconstruction algorithm, such as a linear least square method.

[0031] It should be understood that although the linear least square method is used as the image reconstruction algorithm to reconstruct the instantaneous differential image in the present embodiment, those skilled in the art should understand that other image reconstruction algorithms may also be used in the present disclosure.

[0032] With the instantaneous differential image reconstruction of thoracic cavity blood perfusion taken as an example, the reconstruction process may be as follows: extracting a signal in a predetermined frequency range, i.e., a blood perfusion-related signal, from the electrical impedance measurement signals, and then performing the image reconstruction by using an image reconstruction algorithm on the basis of this blood perfusion-related signal to obtain a blood perfusion image.

[0033] In step S130, an image matrix is constructed on the basis of the instantaneous differential images at the plurality of measurement times. Each column in the image matrix is a vector corresponding to respective instantaneous differential image.

[0034] Here, after the instantaneous differential images corresponding to the plurality of measurement times are obtained, the image matrix is constructed by using the instantaneous differential images corresponding to the plurality of measurement times. This image matrix is:

where I is the image matrix, a(t₁) is a vector corresponding to the instantaneous differential image at a first measurement time, a(t₂) is a vector corresponding to the instantaneous differential image at a second measurement time, and a(t_N) is a vector corresponding to the instantaneous differential image at an N-th measurement time.

[0035] In step S140, a covariance matrix corresponding to the image matrix is determined on the basis of the image matrix.

[0036] Here, a covariance matrix of this image matrix can be calculated after the image matrix is constructed.

[0037] In an optional embodiment, the determining of a covariance matrix corresponding to the image matrix on the basis of the image matrix further comprises the following process.

[0038] On the basis of the image matrix, the covariance matrix corresponding to the image matrix is calculated by using a first predetermined computational equation, wherein the first predetermined computational equation is:

where C is the covariance matrix, I is the image matrix, T is a transpose of the matrix, I is a time-averaged matrix with a size of M * N, and each column element in the time-averaged matrix is

, where M is the number of pixels in each frame of instantaneous differential images, N is the number of measurement times, and a(t_i) is a vector corresponding to the instantaneous differential image at an i-th measurement time.

[0039] Here, each instantaneous differential image can be expressed as a column vector a(t_i), where t_i is an i-th measurement time, i = 1,2, ... , N, and N is the number of measurement times. Each element in the vector a(t_i) represents a pixel value in the image. The image matrix is:I = (a(t₁), a(t₂), ... , a(t_N)), and the time-averaged matrix is a matrix with a size of M * N, and each column element in this matrix is a. Then a covariance matrix of the image matrix can be calculated by the first predetermined computational equation.

[0040] In step S150, according to the covariance matrix, a weight vector of the covariance matrix is obtained.

[0041] In an optional embodiment, the obtaining of a weight vector of the covariance matrix according to the covariance matrix further comprises the following process.

[0042] A weight vector of the covariance matrix is obtained according to the covariance matrix by using a second predetermined computational equation, wherein the second predetermined computational equation is:



where w_* is the weight vector, w is a column vector with the size of M * 1, the value of elements in the column vector is 1 or -1, T is a transpose of the matrix, and C is the covariance matrix.

[0043] Here, the solution of the weight vector w_* is actually to solve the 0-1 quadratic programming problem. Wherein, M is the total number of pixels in the image.

[0044] In step S160, on the basis of the covariance matrix and the weight vector, an electrical impedance state image of the tested human body area is obtained.

[0045] In an optional embodiment, the obtaining of an electrical impedance state image of the tested human body area on the basis of the covariance matrix and the weight vector further comprises the following process.

[0046] The electrical impedance state image of the tested human body area is obtained on the basis of the covariance matrix and the weight vector by using a third predetermined computational equation, wherein the third predetermined computational equation is:

where a_s is the electrical impedance state image, C is the covariance matrix, and w_* is the weight vector.

[0047] Here, the electrical impedance state image can reflect the overall state of the tested human body area over a period of time, thus facilitating the understanding of the images and the overall grasp of the tested human body function by an observer, and thus facilitating subsequent qualitative and quantitative analysis of the tested human body function.

[0048] Figure 2 illustrates an effect picture of the electrical impedance state image of three-dimensional blood perfusion in a human thoracic cavity. As shown in Figure 2, the electrical impedance state image reflects the electrical impedance state of three-dimensional blood perfusion in the human thoracic cavity for a period of time. Based on this image, it is easy for an observer to understand the image and grasp the overall situation of blood perfusion in the tested human body, which facilitates the subsequent qualitative and quantitative analysis of the tested human body function.

Example 2

[0049] According to examples of the present disclosure, an electrical impedance imaging system is also provided, which comprises an acquisition module, an image construction module, a matrix construction module, a covariance matrix calculation module, a weight vector calculation module, and a state image construction module.

[0050] The acquisition module is configured to acquire electrical impedance measurement signals of a tested human body area at a plurality of measurement times.

[0051] The image construction module is configured to construct, for the electrical impedance measurement signal at each measurement time, a corresponding instantaneous differential image on the basis of the electrical impedance measurement signal.

[0052] The matrix construction module is configured to construct an image matrix on the basis of the instantaneous differential images at the plurality of measurement times, wherein each column in the image matrix is a vector corresponding to respective instantaneous differential image.

[0053] The covariance matrix calculation module is configured to determine a covariance matrix corresponding to the image matrix on the basis of the image matrix.

[0054] The weight vector calculation module is configured to obtain a weight vector of this covariance matrix according to the covariance matrix.

[0055] The state image construction module is configured to obtain an electrical impedance state image of the tested human body area on the basis of the covariance matrix and the weight vector.

Example 3

[0056] According to examples of the present disclosure, a storage medium having program code stored thereon is also provided, wherein the electrical impedance imaging method as described in any of the above examples is implemented when the program code is executed by a processor.

Example 4

[0057] According to examples of the present disclosure, an electronic device comprising a memory and a processor is also provided, program code runnable on the processor is stored on the memory, and the electrical impedance imaging method as described in any of the above examples is implemented when the program code is executed by the processor.

[0058] The technical solutions of the present disclosure are described in detail above in conjunction with the drawings. Given that instantaneous electrical impedance change images in the related art can hardly reflect the overall state of the tested human body, the present disclosure provides an electrical impedance imaging method, a system, a storage medium, and an electronic device, an electrical impedance state image reflecting the overall state of the tested human body function over a period of time is reconstructed from electrical impedance measurement signals of the tested human body area at a plurality of measurement times. As can be seen, an electrical impedance state image reflecting the overall state of the tested human body function over a period of time can be obtained by using the electrical impedance imaging method provided by the examples of the present disclosure, thereby facilitating the understanding of the images and the overall grasp of the tested human body function by an observer for subsequent qualitative and quantitative analysis of the tested human body function.

[0059] In the several examples provided in the present application, it should be understood that the disclosed device and method can be implemented in other ways. For example, the device examples described above are merely schematic, e.g., the division of units, which is only a logical functional division, can be performed in other ways in actual implementation. For example, a plurality of units or assemblies can be combined or integrated into another system, or some features can be ignored, or not implemented.

[0060] The units illustrated as isolated components may or may not be physically separated, and the components displayed as units may or may not be physical units, i.e. they may be located in one position or may be distributed to a plurality of network units. Some or all of these units may be selected based on practical needs to achieve the purpose of examples in the present disclosure.

[0061] In addition, each functional unit in each example of the present disclosure may be integrated in a single processing unit, or each functional unit may be present in physical separation, or two or more units may be integrated in a single processing unit. The above integrated units can be implemented in the form of either hardware or software functional units.

[0062] The integrated unit, when implemented in the form of software functional units and sold or used as a separate product, may be stored in a computer readable storage medium. Based on this understanding, the essence of the technical solution of the present disclosure, or in other words, a part thereof contributing to the prior art, or all or parts of the technical solution may be embodied in the form of a software product. The software product is stored in a storage medium and includes a number of instructions to enable an electronic device (which may be a personal computer, a server, or a network device, etc.) to perform all or some of the steps in various examples of the present disclosure. The aforementioned storage medium includes: USB flash drives, portable hard drives, Read-Only Memories (ROM), Random Access Memories (RAM), disks, or compact discs, and various other media that can store a program code.

[0063] Although the present disclosure discloses embodiments as described above, the described contents are only embodiments adopted to facilitate the understanding of the present disclosure and are not intended to limit the present disclosure. Those skilled in the art to which the present disclosure pertains may make any modifications and changes in the form and details of implementation. The protection scope of the present invention is defined in the appended claims.

Claims

1. A computer-implemented electrical impedance imaging method, comprising:

acquiring electrical impedance measurement signals of a tested human body area at a plurality of measurement times (S110);

for the electrical impedance measurement signal at each measurement time, constructing a corresponding instantaneous differential image on the basis of the electrical impedance measurement signal (S120);

constructing an image matrix on the basis of the instantaneous differential images at the plurality of measurement times, wherein each column in the image matrix is a vector corresponding to respective instantaneous differential image and wherein the image matrix is:

where I is the image matrix, a(t₁)is a vector corresponding to the instantaneous differential image at a first measurement time, a(t₂)is a vector corresponding to the instantaneous differential image at a second measurement time, and a(t_N) is a vector corresponding to the instantaneous differential image at an N-th measurement time (S130)

calculating, on the basis of the image matrix, a covariance matrix corresponding to the image matrix by using a first predetermined computational equation, wherein the first predetermined computational equation is:

where C is the covariance matrix, I is the image matrix, T is a transpose of the matrix, I is a time-averaged matrix with a size of M * N, and each column in the time-averaged matrix is

, where M is the number of pixels in each frame of instantaneous differential images, N is the number of measurement times, and a(t_i) is a vector corresponding to the instantaneous differential image at an i-th measurement time and each element in the vector a(t_i) represents a pixel value in the instantaneous differential image (S140);

calculating, according to the covariance matrix, a weight vector of the covariance matrix by using a second predetermined computational equation, wherein the second predetermined computational equation is:

where w_* is the weight vector, w is a column vector with a size of M * 1, the value of elements in the column vector is 1 or -1, T is a transpose of the matrix, and C is the covariance matrix (S150); and

obtaining, on the basis of the covariance matrix and the weight vector, an electrical impedance state image of the tested human body area (S160).

2. The method according to claim 1, wherein the acquiring electrical impedance measurement signals of a tested human body area at a plurality of measurement times further comprises:

fixing an electrode array around the tested human body area, wherein the electrode array comprises a plurality of electrodes; and

exciting the tested human body area by the electrode array and measuring the resulting response.

3. The method according to claim 1, wherein the obtaining, on the basis of the covariance matrix and the weight vector, an electrical impedance state image of the tested human body area, further comprises:

calculating, on the basis of the covariance matrix and the weight vector, the electrical impedance state image of the tested human body area by using a third predetermined computational equation, wherein the third predetermined computational equation is:

where a_s is the electrical impedance state image, C is the covariance matrix and w_* is the weight vector.

4. The method according to claim 1, wherein the constructing, for the electrical impedance measurement signal at each measurement time, a corresponding instantaneous differential image on the basis of the electrical impedance measurement signal, further comprises:

for the electrical impedance measurement signal at each measurement time, extracting a signal in a predetermined frequency range from the electrical impedance measurement signal; and

for each extracted signal in the predetermined frequency range, constructing the corresponding instantaneous differential image on the basis of the extracted signal in the predetermined frequency range by using an image reconstruction algorithm.

5. The method according to claim 4, wherein the signal in the predetermined frequency range is extracted from the electrical impedance measurement signals by using a filter.

6. The method according to claim 4, wherein the extracted signal is a ventilation-related signal or a blood perfusion-related signal.

7. The method according to claim 4, wherein the image reconstruction algorithm comprises a linear least square method.

8. An electrical impedance imaging system, comprising:

an acquisition module, configured to acquire electrical impedance measurement signals of a tested human body area at a plurality of measurement times;

an image construction module, configured to construct, for the electrical impedance measurement signal at each measurement time, a corresponding instantaneous differential image on the basis of the electrical impedance measurement signal;

a matrix construction module, configured to construct an image matrix on the basis of the instantaneous differential images at the plurality of measurement times, wherein each column in the image matrix is a vector corresponding to respective instantaneous differential image and wherein the image matrix is:

where I is the image matrix, a(t₁)is a vector corresponding to the instantaneous differential image at a first measurement time, a(t₂)is a vector corresponding to the instantaneous differential image at a second measurement time, and a(t_N) is a vector corresponding to the instantaneous differential image at an N-th measurement time;

a covariance matrix calculation module, configured to calculate, on the basis of the image matrix, a covariance matrix corresponding to the image matrix by using a first predetermined computational equation, wherein the first predetermined computational equation is:

where C is the covariance matrix, I is the image matrix, T is a transpose of the matrix, I is a time-averaged matrix with a size of M * N, and each column in the time-averaged matrix is

, where M is the number of pixels in each frame of instantaneous differential images, N is the number of measurement times, and a(t_i) is a vector corresponding to the instantaneous differential image at an i-th measurement time and each element in the vector a(t_i) represents a pixel value in the instantaneous differential image;

a weight vector calculation module, configured to calculate, according to the covariance matrix, a weight vector of the covariance matrix by using a second predetermined computational equation, wherein the second predetermined computational equation is:

where w_* is the weight vector, w is a column vector with a size of M * 1, the value of elements in the column vector is 1 or -1, T is a transpose of the matrix, and C is the covariance matrix; and

a state image construction module, configured to obtain, on the basis of the covariance matrix and the weight vector, an electrical impedance state image of the tested human body area.

9. A storage medium having a program code stored thereon, wherein the electrical impedance imaging method according to any one of claims 1 to 7 is implemented when the program code is executed by a processor.

Ansprüche

1. Computerimplementiertes elektrisches Impedanz-Bildgebungsverfahren, umfassend:

Erfassen elektrischer Impedanz-Messsignale eines getesteten menschlichen Körperbereichs zu einer Vielzahl von Messzeiten (S110);

für das elektrische Impedanz-Messsignal zu jeder Messzeit, Konstruieren eines entsprechenden verzögerungsfreien Differentialbilds auf Grundlage des elektrischen Impedanz-Messsignals (S120);

Konstruieren einer Bildmatrix auf Grundlage der verzögerungsfreien Differentialbilder zu der Vielzahl von Messzeiten, wobei jede Spalte in der Bildmatrix ein Vektor ist, der einem jeweiligen verzögerungsfreien Differentialbild entspricht, und wobei die Bildmatrix wie folgt festgelegt ist:

wobei I die Bildmatrix ist, a(t₁) ein Vektor ist, der dem verzögerungsfreien Differentialbild zu einer ersten Messzeit entspricht, a(t₂) ein Vektor ist, der dem verzögerungsfreien Differentialbild zu einer zweiten Messzeit entspricht, und a(t_N) ein Vektor ist, der dem verzögerungsfreien Differentialbild zu einer N-ten Messzeit entspricht (S130),

Berechnen, auf Grundlage der Bildmatrix, einer Kovarianzmatrix, die der Bildmatrix entspricht, unter Verwendung einer ersten vorbestimmten Rechengleichung, wobei die erste vorbestimmte Rechengleichung Folgende ist:

wobei C die Kovarianzmatrix ist, I die Bildmatrix ist, T eine Transponierte der Matrix ist, I eine zeitlich gemittelte Matrix mit einer Größe von M * N ist und für jede Spalte in der zeitlich gemittelten Matrix

gilt, wobei M die Anzahl von Pixeln in jedem Einzelbild von verzögerungsfreien Differentialbildern ist, N die Anzahl von Messzeiten ist und a(t_i) ein Vektor ist, der dem verzögerungsfreien Differentialbild zu einer i-ten Messzeit entspricht, und jedes Element in dem Vektor a(t_i) einen Pixelwert in dem verzögerungsfreien Differentialbild darstellt (S140);

Berechnen, gemäß der Kovarianzmatrix, eines Gewichtungsvektors der Kovarianzmatrix unter Verwendung einer zweiten vorbestimmten

Rechengleichung, wobei die zweite vorbestimmte Rechengleichung die Folgende ist:

wobei w_* der Gewichtungsvektor ist, w ein Säulenvektor mit einer Größe von M * 1 ist, der Wert von Elementen in dem Säulenvektor 1 oder -1 ist, T eine Transponierte der Matrix ist und C die Kovarianzmatrix ist (S150); und Erlangen, auf Grundlage der Kovarianzmatrix und des Gewichtungsvektors, eines elektrischen Impedanz-Zustandsbilds des getesteten menschlichen Körperbereichs (S160).

2. Verfahren nach Anspruch 1, wobei das Erfassen elektrischer Impedanz-Messsignale eines getesteten menschlichen Körperbereichs zu einer Vielzahl von Messzeiten ferner Folgendes umfasst:

Befestigen einer Elektrodenanordnung um den getesteten menschlichen Körperbereich, wobei die Elektrodenanordnung eine Vielzahl von Elektroden umfasst; und

Anregen des getesteten menschlichen Körperbereichs durch die Elektrodenanordnung und Messen der sich ergebenden Reaktion.

3. Verfahren nach Anspruch 1, wobei das Erlangen, auf Grundlage der Kovarianzmatrix und des Gewichtungsvektors, eines elektrischen Impedanz-Zustandsbilds des getesteten menschlichen Körperbereichs ferner Folgendes umfasst:

Berechnen, auf Grundlage der Kovarianzmatrix und des Gewichtungsvektors, des elektrischen Impedanz-Zustandsbilds des getesteten menschlichen Körperbereichs unter Verwendung einer dritten vorbestimmten Rechengleichung, wobei die dritte vorbestimmte Rechengleichung die Folgende ist:

wobei a_s das elektrische Impedanz-Zustandsbild ist, C die Kovarianzmatrix ist und w_* der Gewichtungsvektor ist.

4. Verfahren nach Anspruch 1, wobei das Konstruieren, für das elektrische Impedanz-Messsignal zu jeder Messzeit, eines entsprechenden verzögerungsfreien Differentialbilds auf Grundlage des elektrischen Impedanz-Messsignals ferner Folgendes umfasst:

für das elektrische Impedanz-Messsignal zu jeder Messzeit Extrahieren eines Signals in einem vorbestimmten Frequenzbereich aus dem elektrischen Impedanz-Messsignal; und

für jedes extrahierte Signal in dem vorbestimmten Frequenzbereich Konstruieren des entsprechenden verzögerungsfreien Differentialbilds auf Grundlage des extrahierten Signals in dem vorbestimmten Frequenzbereich unter Verwendung eines Bildrekonstruktionsalgorithmus.

5. Verfahren nach Anspruch 4, wobei das Signal in dem vorbestimmten Frequenzbereich unter Verwendung eines Filters aus den elektrischen Impedanz-Messsignalen extrahiert wird.

6. Verfahren nach Anspruch 4, wobei das extrahierte Signal ein beatmungsbezogenes Signal oder ein durchblutungsbezogenes Signal ist.

7. Verfahren nach Anspruch 4, wobei der Bildrekonstruktionsalgorithmus ein lineares Verfahren der kleinsten Quadrate umfasst.

8. Elektrisches Impedanz-Bildgebungssystem, umfassend:

ein Erfassungsmodul, das dazu konfiguriert ist, elektrische Impedanz-Messsignale eines getesteten menschlichen Körperbereichs zu einer Vielzahl von Messzeiten zu erfassen;

ein Bildkonstruktionsmodul, das dazu konfiguriert ist, für das elektrische Impedanz-Messsignal zu jeder Messzeit ein entsprechendes verzögerungsfreies Differentialbild auf Grundlage des elektrischen Impedanz-Messsignals zu konstruieren;

ein Matrixkonstruktionsmodul, das dazu konfiguriert ist, eine Bildmatrix auf Grundlage der verzögerungsfreien Differentialbilder zu der Vielzahl von Messzeiten zu konstruieren, wobei jede Spalte in der Bildmatrix ein Vektor ist,

der einem jeweiligen verzögerungsfreien Differentialbild entspricht, und wobei die Bildmatrix wie folgt festgelegt ist:

wobei /die Bildmatrix ist, a(t₁) ein Vektor ist, der dem verzögerungsfreien Differentialbild zu einer ersten Messzeit entspricht, a(t₂) ein Vektor ist, der dem verzögerungsfreien Differentialbild zu einer zweiten Messzeit entspricht, und a(t_N) ein Vektor ist, der dem verzögerungsfreien Differentialbild zu einer N-ten Messzeit entspricht;

ein Kovarianzmatrixberechnungsmodul, das dazu konfiguriert ist, auf Grundlage der Bildmatrix unter Verwendung einer ersten vorbestimmten Rechengleichung eine Kovarianzmatrix, die der Bildmatrix entspricht, zu berechnen, wobei die erste vorbestimmte Rechengleichung Folgende ist:

wobei C die Kovarianzmatrix ist, I die Bildmatrix ist, T eine Transponierte der Matrix ist, I eine zeitlich gemittelte Matrix mit einer Größe von M * N ist und für jede Spalte in der zeitlich gemittelten Matrix

gilt, wobei M die Anzahl von Pixeln in jedem Einzelbild von verzögerungsfreien Differentialbildern ist, N die Anzahl von Messzeiten ist und a(t_i) ein Vektor ist, der dem verzögerungsfreien Differentialbild zu einer i-ten Messzeit entspricht, und jedes Element in dem Vektor a(t_i) einen Pixelwert in dem verzögerungsfreien Differentialbild darstellt;

ein Gewichtungsvektorberechnungsmodul, das dazu konfiguriert ist, gemäß der Kovarianzmatrix unter Verwendung einer zweiten vorbestimmten Rechengleichung einen Gewichtungsvektor der Kovarianzmatrix zu berechnen, wobei die zweite vorbestimmte Rechengleichung die Folgende ist:

wobei w_* der Gewichtungsvektor ist, wein Säulenvektor mit einer Größe von M * 1 ist, der Wert von Elementen in dem Säulenvektor 1 oder -1 ist, T eine Transponierte der Matrix ist und C die Kovarianzmatrix ist; und Zustandsbildkonstruktionsmodul, das dazu konfiguriert ist, auf Grundlage der Kovarianzmatrix und des Gewichtungsvektors ein elektrisches Impedanz-Zustandsbild des getesteten menschlichen Körperbereichs zu erlangen.

9. Speichermedium, das einen darauf gespeicherten Programmcode aufweist, wobei das elektrische Impedanz-Bildgebungsverfahren nach einem der Ansprüche 1 bis 7 implementiert wird, wenn der Programmcode durch einen Prozessor ausgeführt wird.

Revendications

1. Procédé d'imagerie d'impédance électrique implémenté par ordinateur, comprenant :

l'acquisition de signaux de mesure d'impédance électrique d'une zone du corps humain testée à une pluralité de temps de mesure (S110) ;

pour le signal de mesure d'impédance électrique à chaque temps de mesure, la construction d'une image différentielle instantanée correspondante sur la base du signal de mesure d'impédance électrique (S120) ;

la construction d'une matrice d'image sur la base des images différentielles instantanées à la pluralité de temps de mesure, dans lequel chaque colonne dans la matrice d'image est un vecteur correspondant à une image différentielle instantanée respective et dans lequel la matrice d'image est :

où I est la matrice d'image, a(t₁) est un vecteur correspondant à l'image différentielle instantanée à un premier temps de mesure, a(t₂) est un vecteur correspondant à l'image différentielle instantanée à un deuxième temps de mesure, et a(t_N) est un vecteur correspondant à l'image différentielle instantanée à un Nième temps de mesure (S130),

le calcul, sur la base de la matrice d'image, d'une matrice de covariance correspondant à la matrice d'image à l'aide d'une première équation de calcul prédéterminée, dans lequel la première équation de calcul prédéterminée est :

où C est la matrice de covariance, I est la matrice d'image, T est une transposée de la matrice, I est une matrice moyennée dans le temps ayant une taille de M * N, et chaque colonne dans la matrice moyennée dans le temps est

, où M est le nombre de pixels dans chaque trame d'images différentielles instantanées, N est le nombre de temps de mesure, et a(t_i) est un vecteur correspondant à l'image différentielle instantanée à un i-ième temps de mesure, et chaque élément dans le vecteur a(t_i) représente une valeur de pixel dans l'image différentielle instantanée (S140) ;

le calcul, selon la matrice de covariance, d'un vecteur de poids de la matrice de covariance à l'aide d'une deuxième équation de calcul prédéterminée, dans lequel la deuxième équation de calcul prédéterminée est :

où w_* est le vecteur de poids, w est un vecteur de colonne ayant une taille de M * 1, la valeur des éléments dans le vecteur de colonne est 1 ou -1, T est une transposée de la matrice, et C est la matrice de covariance (S150) ; et l'obtention, sur la base de la matrice de covariance et du vecteur de poids, d'une image d'état d'impédance électrique de la zone de corps humain testée (S160).

2. Procédé selon la revendication 1, dans lequel l'acquisition de signaux de mesure d'impédance électrique d'une zone de corps humain testée à une pluralité de temps de mesure comprend en outre :

la fixation d'un jeu d'électrodes autour de la zone de corps humain testée, dans lequel le jeu d'électrodes comprend une pluralité d'électrodes ; et

l'excitation, par le jeu d'électrodes, de la zone de corps humain testée et la mesure de la réponse qui en résulte.

3. Procédé selon la revendication 1, dans lequel l'obtention, sur la base de la matrice de covariance et du vecteur de poids, d'une image d'état d'impédance électrique de la zone de corps humain testée, comprend en outre :

le calcul, sur la base de la matrice de covariance et du vecteur de poids, de l'image d'état d'impédance électrique de la zone de corps humain testée à l'aide d'une troisième équation de calcul prédéterminée, dans lequel la troisième équation de calcul prédéterminée est :

où a_s est l'image de l'état d'impédance électrique, C est la matrice de covariance et w_* est le vecteur de poids.

4. Procédé selon la revendication 1, dans lequel la construction, pour le signal de mesure d'impédance électrique à chaque temps de mesure, d'une image différentielle instantanée correspondante sur la base du signal de mesure d'impédance électrique, comprend en outre :

pour le signal de mesure d'impédance électrique à chaque temps de mesure, l'extraction d'un signal dans une plage de fréquences prédéterminée à partir du signal de mesure d'impédance électrique ; et

pour chaque signal extrait dans la plage de fréquences prédéterminée, la construction de l'image différentielle instantanée correspondante sur la base du signal extrait dans la plage de fréquences prédéterminée à l'aide d'un algorithme de reconstruction d'image.

5. Procédé selon la revendication 4, dans lequel le signal dans la plage de fréquences prédéterminée est extrait des signaux de mesure d'impédance électrique à l'aide d'un filtre.

6. Procédé selon la revendication 4, dans lequel le signal extrait est un signal lié à la ventilation ou un signal lié à la perfusion sanguine.

7. Procédé selon la revendication 4, dans lequel l'algorithme de reconstruction d'image comprend une méthode linéaire des moindres carrés.

8. Système d'imagerie d'impédance électrique, comprenant :

un module d'acquisition, configuré pour acquérir des signaux de mesure d'impédance électrique d'une zone de corps humain testée à une pluralité de temps de mesure ;

un module de construction d'image, configuré pour construire, pour le signal de mesure l'impédance électrique à chaque temps de mesure, une image différentielle instantanée correspondante sur la base du signal de mesure l'impédance électrique ;

un module de construction de matrice, configuré pour construire une matrice d'image sur la base des images différentielles instantanées à la pluralité de temps de mesure, dans lequel chaque colonne dans la matrice d'image est un vecteur correspondant à l'image différentielle instantanée respective et dans lequel la matrice d'image est :

où I est la matrice d'image, a(t₁) est un vecteur correspondant à l'image différentielle instantanée à un premier temps de mesure, a(t₂) est un vecteur correspondant à l'image différentielle instantanée à un deuxième temps de mesure, et a(t_N) est un vecteur correspondant à l'image différentielle instantanée à un Nième temps de mesure ;

un module de calcul de matrice de covariance, configuré pour calculer, sur la base de la matrice d'image, une matrice de covariance correspondant à la matrice d'image à l'aide d'une première équation de calcul prédéterminée, dans lequel la première équation de calcul prédéterminée est :

où C est la matrice de covariance, I est la matrice d'image, T est une transposée de la matrice, I est une matrice moyennée dans le temps ayant une taille de M * N, et chaque colonne dans la matrice moyennée dans le temps est

, où M est le nombre de pixels dans chaque trame d'images différentielles instantanées, N est le nombre de temps de mesure, et a(t_i) est un vecteur correspondant à l'image différentielle instantanée à un i-ième temps de mesure, et chaque élément dans le vecteur a(t_i) représente une valeur de pixel dans l'image différentielle instantanée ;

un module de calcul de vecteur de poids, configuré pour calculer, selon la matrice de covariance, un vecteur de poids de la matrice de covariance à l'aide d'une deuxième équation de calcul prédéterminée, dans lequel la deuxième équation de calcul prédéterminée est :

où w_* est le vecteur de poids, w est un vecteur de colonne ayant une taille de M * 1, la valeur des éléments dans le vecteur de colonne est 1 ou -1, T est une transposée de la matrice, et C est la matrice de covariance ; et

un module de construction d'image d'état, configuré pour obtenir, sur la base de la matrice de covariance et du vecteur de poids, une image d'état d'impédance électrique de la zone de corps humain testée.

9. Support de stockage sur lequel est stocké un code de programme, dans lequel le procédé d'imagerie d'impédance électrique selon l'une quelconque des revendications 1 à 7 est implémenté lorsque le code de programme est exécuté par un processeur.

Drawing